ABSTRACT
One interesting phenomenon of Chrysanthemum morifolium tea is its formation of a green or dark green color after hours of brewing, and it is important to study the compounds that form this color and whether they might be involved in health benefits. Non-targeted metabolomics could clearly distinguish between green and non-green species by sparse partial least squares discriminant analysis (sPLS-DA) and heat-mapping. We found that the pH was the primary factor in the formation of the green color. Two green precursors (GP1 and GP2) were separated and purified with preparative HPLC. FT-IR analysis and the saccharide content analysis showed that GP1 had the typical characteristics of saccharides. GP2 was identified as chlorogenic acid by ESI-Q-TOF/MS and NMR. We raised the formation process of green substances was caused by the hydrolysates of chlorogenic acid reacting with glycosides or groups attached to the saccharides, which suggests a new mechanism for color-forming reactions.
Subject(s)
Chrysanthemum/chemistry , Tea/chemistry , Chromatography, High Pressure Liquid , Color , Flowers/chemistry , Glycosides/analysis , Least-Squares Analysis , Plant Extracts/chemistry , Spectroscopy, Fourier Transform InfraredABSTRACT
One interesting phenomenon of Chrysanthemum morifolium tea is its formation of green or dark green color after hours of brewing. We investigated the greening reaction and its bioactivities, including an analysis of the green compounds. Results showed that the green color was due to a decrease in the L* (lightness), b* (yellowness/blueness), chroma values and an increase in hue angle. The green substances were found to be substances with similar polarities and unstable in acidic conditions. There was no significant difference (pâ¯<â¯0.01) in antioxidant activity between non-green and green samples. The green substances did not lead to cytotoxicity in PC12 cells at low concentrations, but at high concentrations, they caused a significant (pâ¯<â¯0.01) decrease in cell viability. The saccharide percentage and FT-IR results showed that the greening reaction was affected by the glycosides or groups attached to the saccharides, which might suggest a new mechanism for color-forming reactions.
Subject(s)
Chrysanthemum/chemistry , Plant Extracts/chemistry , Animals , Antioxidants/chemistry , Cell Survival/drug effects , Chromatography, High Pressure Liquid , Chrysanthemum/metabolism , Color , Flowers/chemistry , Flowers/metabolism , PC12 Cells , Plant Extracts/pharmacology , Rats , Spectroscopy, Fourier Transform InfraredABSTRACT
Tea brewed from chrysanthemum flowers has been widely used in Chinese medicine. The possibly medicinal compounds in Chrysanthemum morifolium tea can be purified by preparative high performance liquid chromatography (HPLC), but this is usually done with acidic conditions, which leads to the hydrolysis of glycosides. In hopes of avoiding this hydrolysis, we explored the effect of weakly basic conditions on the separation and purification of flavonoids and glycosides from Chrysanthemum morifolium. We also explored the effects of weakly basic conditions on chlorogenic acid (3-CQA) and apigenin-7-O-glucoside (A7G). Our results show that the concentration of the weakly basic ammonium hydrogen carbonate and time had no significant effect on A7G, p < 0.01, but it had a significant effect on 3-CQA, p < 0.01. HPLC and ultraviolet (UV) analysis showed that the structure of 3-CQA is destroyed in weakly basic conditions. Caffeic acid, quinic acid, and 3,4-dihydroxymandelic acid, which is a hydrolysate of 3-CQA, were identified by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The results showed that weakly basic conditions could be used for the purification of flavonoids and glycosides but not for caffeoylquinic acids. Moreover, our work clarified the hydrolysis behaviour of caffeoylquinic acids, which can be helpful for research into their functional aspects.
